# -*- coding: utf-8 -*-
# Part of Odoo. See LICENSE file for full copyright and licensing details.

import logging
import random
import threading

from datetime import datetime
from dateutil.relativedelta import relativedelta

from odoo import api, fields, models, tools
from odoo.tools import exception_to_unicode
from odoo.tools.translate import _

_logger = logging.getLogger(__name__)

_INTERVALS = {
    'hours': lambda interval: relativedelta(hours=interval),
    'days': lambda interval: relativedelta(days=interval),
    'weeks': lambda interval: relativedelta(days=7*interval),
    'months': lambda interval: relativedelta(months=interval),
    'now': lambda interval: relativedelta(hours=0),
}


class EventTypeMail(models.Model):
    """ Template of event.mail to attach to event.type. Those will be copied
    upon all events created in that type to ease event creation. """
    _name = 'event.type.mail'
    _description = 'Mail Scheduling on Event Category'

    event_type_id = fields.Many2one(
        'event.type', string='Event Type',
        ondelete='cascade', required=True)
    notification_type = fields.Selection([('mail', 'Mail')], string='Send', default='mail', required=True)
    interval_nbr = fields.Integer('Interval', default=1)
    interval_unit = fields.Selection([
        ('now', 'Immediately'),
        ('hours', 'Hours'), ('days', 'Days'),
        ('weeks', 'Weeks'), ('months', 'Months')],
        string='Unit', default='hours', required=True)
    interval_type = fields.Selection([
        ('after_sub', 'After each registration'),
        ('before_event', 'Before the event'),
        ('after_event', 'After the event')],
        string='Trigger', default="before_event", required=True)
    template_id = fields.Many2one(
        'mail.template', string='Email Template',
        domain=[('model', '=', 'event.registration')], ondelete='restrict',
        help='This field contains the template of the mail that will be automatically sent')

    @api.model
    def _get_event_mail_fields_whitelist(self):
        """ Whitelist of fields that are copied from event_type_mail_ids to event_mail_ids when
        changing the event_type_id field of event.event """
        return ['notification_type', 'template_id', 'interval_nbr', 'interval_unit', 'interval_type']


class EventMailScheduler(models.Model):
    """ Event automated mailing. This model replaces all existing fields and
    configuration allowing to send emails on events since Odoo 9. A cron exists
    that periodically checks for mailing to run. """
    _name = 'event.mail'
    _rec_name = 'event_id'
    _description = 'Event Automated Mailing'

    event_id = fields.Many2one('event.event', string='Event', required=True, ondelete='cascade')
    sequence = fields.Integer('Display order')
    notification_type = fields.Selection([('mail', 'Mail')], string='Send', default='mail', required=True)
    interval_nbr = fields.Integer('Interval', default=1)
    interval_unit = fields.Selection([
        ('now', 'Immediately'),
        ('hours', 'Hours'), ('days', 'Days'),
        ('weeks', 'Weeks'), ('months', 'Months')],
        string='Unit', default='hours', required=True)
    interval_type = fields.Selection([
        ('after_sub', 'After each registration'),
        ('before_event', 'Before the event'),
        ('after_event', 'After the event')],
        string='Trigger ', default="before_event", required=True)
    template_id = fields.Many2one(
        'mail.template', string='Email Template',
        domain=[('model', '=', 'event.registration')], ondelete='restrict',
        help='This field contains the template of the mail that will be automatically sent')
    scheduled_date = fields.Datetime('Scheduled Sent Mail', compute='_compute_scheduled_date', store=True)
    mail_registration_ids = fields.One2many('event.mail.registration', 'scheduler_id')
    mail_sent = fields.Boolean('Mail Sent on Event', copy=False)
    done = fields.Boolean('Sent', compute='_compute_done', store=True)

    @api.depends('mail_sent', 'interval_type', 'event_id.registration_ids', 'mail_registration_ids')
    def _compute_done(self):
        for mail in self:
            if mail.interval_type in ['before_event', 'after_event']:
                mail.done = mail.mail_sent
            else:
                mail.done = len(mail.mail_registration_ids) == len(mail.event_id.registration_ids) and all(mail.mail_sent for mail in mail.mail_registration_ids)

    @api.depends('event_id.date_begin', 'interval_type', 'interval_unit', 'interval_nbr')
    def _compute_scheduled_date(self):
        for mail in self:
            if mail.interval_type == 'after_sub':
                date, sign = mail.event_id.create_date, 1
            elif mail.interval_type == 'before_event':
                date, sign = mail.event_id.date_begin, -1
            else:
                date, sign = mail.event_id.date_end, 1

            mail.scheduled_date = date + _INTERVALS[mail.interval_unit](sign * mail.interval_nbr) if date else False

    def execute(self):
        for mail in self:
            now = fields.Datetime.now()
            if mail.interval_type == 'after_sub':
                # update registration lines
                lines = [
                    (0, 0, {'registration_id': registration.id})
                    for registration in (mail.event_id.registration_ids - mail.mapped('mail_registration_ids.registration_id'))
                ]
                if lines:
                    mail.write({'mail_registration_ids': lines})
                # execute scheduler on registrations
                mail.mail_registration_ids.execute()
            else:
                # Do not send emails if the mailing was scheduled before the event but the event is over
                if not mail.mail_sent and mail.scheduled_date <= now and mail.notification_type == 'mail' and \
                        (mail.interval_type != 'before_event' or mail.event_id.date_end > now):
                    mail.event_id.mail_attendees(mail.template_id.id)
                    mail.write({'mail_sent': True})
        return True

    @api.model
    def _warn_template_error(self, scheduler, exception):
        # We warn ~ once by hour ~ instead of every 10 min if the interval unit is more than 'hours'.
        if random.random() < 0.1666 or scheduler.interval_unit in ('now', 'hours'):
            ex_s = exception_to_unicode(exception)
            try:
                event, template = scheduler.event_id, scheduler.template_id
                emails = list(set([event.organizer_id.email, event.user_id.email, template.write_uid.email]))
                subject = _("WARNING: Event Scheduler Error for event: %s", event.name)
                body = _("""Event Scheduler for:
  - Event: %(event_name)s (%(event_id)s)
  - Scheduled: %(date)s
  - Template: %(template_name)s (%(template_id)s)

Failed with error:
  - %(error)s

You receive this email because you are:
  - the organizer of the event,
  - or the responsible of the event,
  - or the last writer of the template.
""",
                         event_name=event.name,
                         event_id=event.id,
                         date=scheduler.scheduled_date,
                         template_name=template.name,
                         template_id=template.id,
                         error=ex_s)
                email = self.env['ir.mail_server'].build_email(
                    email_from=self.env.user.email,
                    email_to=emails,
                    subject=subject, body=body,
                )
                self.env['ir.mail_server'].send_email(email)
            except Exception as e:
                _logger.error("Exception while sending traceback by email: %s.\n Original Traceback:\n%s", e, exception)
                pass

    @api.model
    def run(self, autocommit=False):
        schedulers = self.search([('done', '=', False), ('scheduled_date', '<=', datetime.strftime(fields.datetime.now(), tools.DEFAULT_SERVER_DATETIME_FORMAT))])
        for scheduler in schedulers:
            try:
                with self.env.cr.savepoint():
                    # Prevent a mega prefetch of the registration ids of all the events of all the schedulers
                    self.browse(scheduler.id).execute()
            except Exception as e:
                _logger.exception(e)
                self.invalidate_cache()
                self._warn_template_error(scheduler, e)
            else:
                if autocommit and not getattr(threading.currentThread(), 'testing', False):
                    self.env.cr.commit()
        return True


class EventMailRegistration(models.Model):
    _name = 'event.mail.registration'
    _description = 'Registration Mail Scheduler'
    _rec_name = 'scheduler_id'
    _order = 'scheduled_date DESC'

    scheduler_id = fields.Many2one('event.mail', 'Mail Scheduler', required=True, ondelete='cascade')
    registration_id = fields.Many2one('event.registration', 'Attendee', required=True, ondelete='cascade')
    scheduled_date = fields.Datetime('Scheduled Time', compute='_compute_scheduled_date', store=True)
    mail_sent = fields.Boolean('Mail Sent')

    def execute(self):
        now = fields.Datetime.now()
        todo = self.filtered(lambda reg_mail:
            not reg_mail.mail_sent and \
            reg_mail.registration_id.state in ['open', 'done'] and \
            (reg_mail.scheduled_date and reg_mail.scheduled_date <= now) and \
            reg_mail.scheduler_id.notification_type == 'mail'
        )
        for reg_mail in todo:
            reg_mail.scheduler_id.template_id.send_mail(reg_mail.registration_id.id)
        todo.write({'mail_sent': True})

    @api.depends('registration_id', 'scheduler_id.interval_unit', 'scheduler_id.interval_type')
    def _compute_scheduled_date(self):
        for mail in self:
            if mail.registration_id:
                date_open = mail.registration_id.date_open
                date_open_datetime = date_open or fields.Datetime.now()
                mail.scheduled_date = date_open_datetime + _INTERVALS[mail.scheduler_id.interval_unit](mail.scheduler_id.interval_nbr)
            else:
                mail.scheduled_date = False
